On arrival, the young guests were given purple Jamie Oliver food hampers with finger sandwiches, a salad, fruit from around the Commonwealth and British strawberries.

But the centrepiece of the afternoon is a show which follows the hunt to find who stole the Queen's bag containing her speech.

The cast of Harry Potter attended the Queen's party

Among the many stars who've worked on the production are Sophie Dahl, Ronnie Corbett, Jonathan Ross, Kelly Osbourne, Martin Clunes, Jerry Hall, Anthony Head and Patsy Kensit.

Some corgis - not the Queen's - are also involved, and as stars, have their own trailers, right behind the stage.

In the end, good prevails and the Queen gets her handbag back, and is able to appear on stage to make that vital speech.

"I am delighted to have my handbag back, I do like happy endings," she says.

'So amazing'

For the lucky guests, the afternoon is pure magic. "It's so amazing","I can't believe it!", "It's something I'm going to remember for ever and ever and ever", were some of the comments.

But many who didn't get tickets will also benefit - the party highlights a campaign to bring literature into the lives of disadvantaged and hospitalised children.

Twelve thousand books have been donated by publishers to a book pool established through the National Literacy Trust, and some of the writers who read to youngsters in the authors' tent during the party will give readings in hospitals and schools.

Harry Potter author JK Rowling and Jacqueline Wilson were amongst a group of writers at the party.